The present invention relates to a technique for manufacturing a semiconductor integrated circuit device and, more particularly, to a technique which is effective in achieving anticorrosion of metal wirings formed by a chemical mechanical polishing (CMP) method.
Japanese Patent Laid-open No. 135192/1995 (hereinafter referred to as “Hayakawa”) has disclosed a post-polishing method which makes it possible to lower the particle level after polishing treatment on a wafer by performing, without drying the wafer, a series of steps including chemical mechanical polishing, followed by wafer inverting standby, physical cleaning, chemical-cleaning (or spin-cleaning) and rinsing treatments. In the polishing apparatus to be used in this process, a wafer mounting portion in the polishing unit is made to have a construction which is capable of keeping the wafer wet, and an inter-unit wet conveying mechanism is used for conveying wafers among a polishing unit, a cleaning unit and a rinsing/drying unit, whereas an in-unit wet conveying mechanism is used for conveying wafers between the individual cleaning chambers in the cleaning unit.
A CMP apparatus for an oxide film comprising a wafer feeding portion, a polishing portion, a wafer extracting portion and a dress unit is disclosed on pp. 53 to 55 of Electronic Materials, issued in May, 1996, by the Association of Industrial Researches (hereinafter referred to as “Ohmura et al.”). In this apparatus, the wafer is conveyed by a conveyor robot from a load cassette to a polishing portion and is polished. The polished wafer is then scrub-cleaned on its front and back sides with pure water, is stocked in an unload cassette, and thereafter, is stocked in water.
On pp. 62 to 65 of Electronic Materials, issued in May, 1996 (hereinafter referred to as “Tsujimura et al.”), there is disclosed a technique for the transfer of a wafer in an underwater stock from a polishing step to a post-cleaning treatment (aiming at removing undesired particles such as abrasive grains introduced at the polishing time from the wafer surface and generally conducted before the wafer surface is naturally dried).
On pp. 33 to 35 of Electronic Materials, issued in May, 1996 (hereinafter referred to as “Hirakura”), there is disclosed a CMP apparatus comprising a polishing disc (or platen) for performing a primary polishing treatment, a polishing disc for performing a second polishing (or buff polishing) treatment, a cleaning station for cleaning the polished wafer with water and a brush, and an unloader for stocking the wafer in a submerged state.
Japanese Patent Laid-open No. 64594/1996 (hereinafter referred to as “Shibuki”) has disclosed a metal CMP process using a slurry containing an anticorrosive agent, such as BTA, so as to prevent corrosion of the metal, which might otherwise occur in the metal CMP process.